Modeling the Impact of Electrolyte Flow on Heat Management in a Li-Ion Convection Cell

Abstract

In response to challenges in the thermal management of lithium-ion batteries (LIBs), we investigate the concept of circulating electrolyte through the porous electrodes and separator to facilitate effective, uniform, and real-time temperature regulation. We show, through physics-based electrothermal modeling and dimensional analysis of a single, planar LIB cell, that electrolyte convection can simultaneously draw heat from the cell and suppress heat generation from entropy change, charge-transfer, and ohmic losses, and that the cell temperature rise can be effectively mitigated when heat removal matches or exceeds heat generation. These findings distinguish internal convection from external surface cooling approaches used in conventional thermal management that often lead to a tradeoff between heat and mass transport. In a simulated exemplary 5.7-C case, a LIB cell with stationary electrolyte must stop discharging at only 54% of its capacity due to cell temperature rise to an upper threshold (325 K); with sufficient electrolyte flow (∼1 μm s−1 for a single cell, or a residence time of ∼200 s), the cell can be maintained below 315 K while delivering 98% of its capacity. Finally, to illustrate the potential for dynamic temperature regulation, we simulate scenarios where cells already experiencing self-heating can instantly arrest temperature rise with the onset of convection.